This invention relates to the construction of radiation shielded enclosures of the type designed to have an interior that may be relatively isolated from radio interference and other radiation. The invention is particularly directed to the construction of door joints for such enclosures for the purpose of increasing the resistance to radiation penetration through the joints between the edges of the door and its frame.
U.S. Pat. No. 4,817,337 (hereinafter referred to as the '337 patent) issued on Apr. 4, 1989 to Lahita shows a radiation resistant door seal. It is to be noted that the Lahita of the '337 patent is the inventor of the present invention. The present application advances the art beyond that disclosed in the '337 patent by teaching, disclosing and claiming resilient arch shaped contact members absent the bowed forward section and edge sections associated with the resilient contact members required of the '337 patent. Further, the instant invention provides, discloses and claims a third arch-like member attached to a door section which in combination provides for additional electrical contact areas to that offered in the '337 patent as well as obviating a deficiency in the '337 patent which requires contact members to compress or otherwise displace in a direction in opposition to shielding pressure induced by a door blade when inserting a rigid blade member between the contact members. Succinctly stated, the enhancements to the art taught by the instant application advance the teachings of the '337 patent by providing additional shielding and electrical contact surfaces.
Shielding effectiveness requirements are ever increasing such that standards that were acceptable in the past may be totally unacceptable today. For example, the door joint must be as resistant to radiation leakage as the enclosure itself.
A door and frame construction herein disclosed provides 360 degree environmental protection against air, sound and dust and radiation (non-ionizing) protection about the periphery of the door. Tapering of channel side walls to complement the different contact sections increases surface contact, reduces friction, and improves radiation shielding via the metal-to-metal contacting between contact spring fingers. A knife-edge shoulder in each opposed channel side wall increases contact with its contact plate, forms and cooperates to hold its contact plate in the channel. Further, tapered side walls reduce friction forces resisting door closure and increase conductive paths by affording a larger contacting surface of the contact plates with the blade.
Consequently, it is an object of the instant invention to provide a door and frame construction which provides 360 degrees of environmental protection against air, sound, dust and radiation protection around the periphery of the door.
It is a further object of the instant invention to provide, teach and claim the tapered channel walls to compliment different contact sections which reduce friction and improve radiation shielding by a metal-to-metal contacting between spring fingers.
Another object of the instant invention is to provide, teach and claim a knife-edge shoulder in each opposed channel on the frame member which biases contact members rearwardly when blade-like structure is inserted between contact members and thereby further easing/orienting; door closing sealing.
Yet it is another object of the instant invention to teach an improved radiation resistant door seal which provides tapered sidewalls to reduce friction, forces resistant door closure and increase conductive paths by affording a larger contacting surface of contact plates with an insertion blade.
An additional object of the instant invention is to teach and claim an improved radiation resistant door seal which facilitates contact member directional compression in a direction of that taught by the '357 patent.
Other objects and further scope of the applicability of the present invention will become apparent from the detailed description to follow, taken in conjunction with the accompanying drawings wherein like parts are designated by like reference numerals.